The present invention relates generally to refractometers for measuring refractive index of a substance, and more particularly to an automatic refractometer that includes a completely fluid-sealed housing for easy cleaning without sacrificing the capability to download measurement data to a computer.
Refractometers are widely used for quality control in industry for measuring sugar concentrations (Brix scale) of fruits, fruit juices, soft drinks and other food products; measuring concentrations of water soluble cutting fluids and other lubricants; testing the freeze point of propylene glycol and ethylene glycol antifreeze solutions; measuring the boiling point and percent water content of brake fluids; testing salinity of sea water; and for other refractive-index based measurements. Because refractometers come into contact with the above-mentioned fluids both during testing and as a natural consequence of being stored in industrial environments, they require frequent cleaning. It is therefore desirable to protect internal optics and electronics (in the case of automatic refractometers) from exposure to harmful test fluids and cleaning fluids.
While many automatic refractometers on the market today are substantially fluid-sealed, they suffer the drawback that a connection port for connecting a data cable to the instrument for downloading digital measurement data to a computer is exposed to test samples, environmental fluids, and cleaning fluids. Therefore, neatness during use and care during cleaning are required to prevent damage to the connection port. In non-automatic refractometers and refractometers without data downloading capability, completely fluid-sealed housings are known.
Therefore, it is an object of the present invention to improve an automatic refractometer of a type that provides digital measurement data by enclosing the refractometer components in a completely fluid-sealed housing, without destroying the refractometer""s capability to download measurement data to a computer.
To meet this object, a refractometer of the present invention is provided with a completely fluid-sealed housing, and a wireless transmitter is among the components enclosed within the housing. Digital measurement data are thereby transmitted as optical pulse signals through a communication window in the housing to a corresponding receiver connected to a computer. In a preferred embodiment, infra-red signal transmission is in accordance with IrDA (Infrared Data Association) hardware standards.
The housing includes an upper housing portion having a sample well opening and a display panel recess, a display/button panel fitted to reside in the display panel recess, a sample well received in the sample well opening, a lower housing portion including a window recess and a battery opening, the aforementioned communication window fitted to reside in the window recess, and a battery cover threadably attached to the lower housing portion to cover the battery opening. Fluid sealing O-rings are provided at connections between the upper and lower housing portions, between the sample well and the upper housing portion, and between the battery cover and the lower housing portion.